1. Technical Field
Embodiments of this disclosure relate to a liquid ejection head and an image forming apparatus incorporating the liquid ejection head.
2. Description of the Related Art
Image forming apparatuses are used as, for example, copiers, printers, facsimile machines, and multi-functional devices having at least one of the foregoing capabilities. As one type of image forming apparatus, for example, an image forming apparatus employing a liquid ejection recording method is known to use a recording head including a liquid ejection head (droplet ejection head) for ejecting droplets of ink, such as an ink-jet recording device. In the liquid ejection head, channels for liquid (ink channels) are formed by joining members for forming the channel (hereinafter referred to as “channel-forming members”) with each other via an adhesive agent. In this case, its bonding interface (joint interface) is a very small region. However, since the region is exposed to ink, the region needs to have a bonding function to prevent peeling-off of the channel-forming members from each other even when the region is in a liquid-contacting state in which the region contacts the ink.
When the channel-forming members or other ink-contacting members are eluted out and swelled due to for example, ink, the image forming apparatus is largely changed in liquid-jetting property so that an image quality can not be maintained satisfactorily.
Thus, the following has been performed: a surface treatment film is formed onto the front surface of the channel-forming members, this film being capable of improving the front surface in adhesiveness; or the front surface of the channel-forming members is activated by irradiation with plasma.
Known are, for example, a technique of forming, as the surface treatment film, an organic film made of, for example, polyimide or polyparaxylene (JP-2012-091381-A); and a technique of forming, as the surface treatment film, a SiO2 film (JP-2004-098310-A).
Known is also a member that has a substrate (base material) and a joint film and can be joined with an opposite substrate (another adherend), in which: the joint film contains a metal atom and an oxygen atom bonded to the metal atom; an eliminating group that is bonded to at least one of the metal atom and the oxygen atom is introduced into the vicinity of the front surface of the joint film; and by radiation of ultraviolet rays thereto, the eliminating group present in the vicinity of the front surface is eliminated from at least one of the metal atom and the oxygen atom so that the joint film can exhibit, onto the front surface thereof, adhesiveness onto the opposite substrate (JP-2009-046541-A).
As disclosed in JP-2012-091381-A, however, when an organic film is used as the surface treatment film, the organic film may not fully block the permeation of water. Thus, a material that is not easily corroded with ink or the like is used for the channel-forming members.
In addition, the SiO2 film as the surface treatment film is converted into a hydroxide by a strongly alkaline liquid, so that the film is easily ionized to be eluted out into the liquid. As a result, the channel-forming members of the film may be damaged.
A metal, such as Ni or Ti, or an alloy material, such as stainless steel (SUS), may be used for the surface treatment film. However, when the film contacts an acidic liquid, the film is oxidized and often easily ionized. Use of a material that is not easily dissolved, such as SUS, may reduce a bonding performance thereof to an adhesive agent.